The present invention relates to ultrasonic gas flow meters and, more particularly, to an ultrasonic gas flow meter housing which facilitates interconnection with other gas flow meter components to provide a multi-configuration system.
Ultrasonic gas flow meters are generally well known. Such meters commonly utilize a technique in which the difference between the time of travel of an ultrasonic wave upstream in a flowing gas and the time of travel of an ultrasonic wave downstream in the flowing gas is used to determined the flow rate of the gas. However, other techniques are also known and used.
Accumulation of liquids in the housings of ultrasonic gas flow meters can occur with sufficient frequency and in sufficient quantity to interfere with accurate gas flow measurement. In such instances the excessive liquid presents a service and maintenance problem for the gas utilities which maintain such meters, and therefore acts as a potential deterrent to successful widespread introduction and use of ultrasonic gas flow meters. The standard attachment position for residential size gas meters is with the inlet and outlet piping connections positioned on the top of the meter case or housing. In this position, the meter housing can become an accumulator for any liquids that are being transported by the flowing gas. In such ultrasonic gas flow meters if the liquid enters the area through which ultrasonic signals pass, the gas flow volume will tend to be measured inaccurately.
Thus, in certain applications there is a need for positioning the inlet and outlet piping connections on the bottom of the meter housing in order to permit the connections to effectively act as drains for any liquids that may enter the meter. However, this housing configuration presents a problem in many areas where the majority of gas meter installation sites still include downwardly extending inlet and outlet piping positioned for entry into the top of a gas meter housing. Utilizing two different gas meter housing configurations, one with top openings and one with bottom openings, would increase manufacturing costs and would be less well received by the gas utilities.
Accordingly, it would be desirable to provide a gas meter housing configured to reduce liquid accumulation therein when installed. It would also be desirable to provide a gas meter housing adapted for installation in at least two different positions within ultrasonic gas meter systems, thereby providing a single housing useful in multiple installation schemes.
The present invention is an ultrasonic gas meter housing member configured to provide an associated multi-configuration ultrasonic gas meter assembly. In a preferred embodiment of the invention the housing member is installable in an ultrasonic gas flow meter which includes an internal flow measurement tube along which gas travels for flow measurement, the tube having an inlet end and an outlet end. The ultrasonic gas meter housing member includes a closed back portion generally rectangular in shape and a front portion spaced from the back portion to define a space for receiving the internal flow measurement tube such that the tube extends substantially along at least a portion of a longitudinal axis of the housing member. First, second, third, and fourth wall portions extending between the back portion and the front portion, the first wall portion having a first opening and a second opening therethrough for connection of the housing member to a gas inlet pipe and a gas outlet pipe, the first and second openings facing in substantially the same direction. The gas meter housing member is symmetrical about a plane which divides the housing member into a first half and a second half, the plane being perpendicular to the longitudinal axis. The symmetrical configuration enables the housing member to receive the flow measurement tube in both a first orientation in which the first and second opening face in a first direction and the inlet end of the flow measurement tube is positioned in the first half of the housing member and the outlet end is positioned in the second half, and a second orientation in which the first and second opening face in a second direction substantially opposite to the first direction and the inlet end of the flow measurement tube is positioned in the second half of the gas meter housing member and the outlet end is positioned in the first half. The first and second orientations are particularly useful in enabling the housing member to be used both in gas meter installation sites where the gas pipes extend downward and in gas meter installation sites where the gas pipes extend upward, so that two different housing configurations need not be provided. Further, in installations where the gas pipes extend upward, the first and second openings through the housing member will face downward and will prevent the build up of liquids within the meter by allowing them to drain.
In another aspect of the invention, a multi-configuration ultrasonic gas meter assembly is provided and includes a first housing member having a back enclosure portion, a front portion spaced from the back enclosure portion to define an internal space, and at least one wall portion extending between the back enclosure portion and the front portion, at least one wall portion having a first opening and a second opening therethrough for connection to a gas inlet pipe and a gas outlet pipe. A gas flow measurement tube is provided for positioning at least partially within the internal space of the first housing member and has a gas inlet end and a gas outlet end. At least one ultrasonic transducer is positioned proximate the gas flow measurement tube for directing an ultrasonic signal along at least a portion of a length of the gas flow measurement tube. An orientation between the first housing member and the measurement tube is selectable between at lest two configurations as necessary for attachment of the gas inlet pipe and the gas outlet pipe, and includes a first assembly configuration in which the first and second openings face in a first direction and gas travels in the first opening, through the gas flow measurement tube from the inlet end to the outlet end, and out of the second opening, and a second assembly configuration in which the first and second openings face in a second direction which is substantially opposite the first direction and in which gas travels in the second opening, through the gas flow measurement tube from the inlet end to the outlet end, and out of the first opening. As above, the two assembly configurations facilitate installation of the gas meter assembly both in gas meter installation sites where the gas pipes extend downward and in gas meter installation sites where the gas pipes extend upward.
Accordingly, it is an object of the present invention to provide an ultrasonic gas meter housing member configured for attachment to both downwardly extending gas pipes and upwardly extending gas pipes; a multi-configuration ultrasonic gas meter assembly; an ultrasonic gas meter housing positionable to permit drainage of fluid therefrom; and a method of manufacturing an improved ultrasonic gas meter housing member. Other objects and advantages of the present invention may be ascertained from a review of the following description and drawings.